Rob, I would imagine getting an insightful opinion on the differences in these two models might be challenging. Most people will own one or the other, and have no opportunity to audition each of them in the same system.
That being said, the MKII looks to be a bit more slick in terms of its cosmetic, which is one area that seems to get upgraded in each iteration. It has a third knob on the front, for the power on/off, whereas on the DJH, it is on the rear of the unit. A tried and true purist might argue that having the power switch on the rear of the unit might be preferable sonically as it probably keeps the AC away from the rest of the unit more than a front panel switch would.
The MKII version also uses a different rectifier tube, which tube would be better? I don't know, though the MKII's is seen on more traditional tube pre/power amplifiers.
And, having not had both of them here, I am not sure which version comes out ahead in totality as far as sonics go.
I can say that my friend The Doctor (Mechans) had his basic version upgraded to more or less DJH status by a buddy of ours, who seriously upgraded the parts quality from middling to very, very good. The reported improvement from both of them was it was quite subtle. Evidently, the magic in this design lies in the circuit...